Electric heater

ABSTRACT

A cartridge or band heater having an internally threaded bushing secured thereof affording a secure mounting for electric wires or a conduit containing such wires.

United States Patent 1191 Wallstrom Aug. 20, 1974 1 ELECTRIC HEATER 2,091,054 3/1937 Petrie 330/103 c x 2,269,194 1/1942 Finlayson 338/238 x [75] Invent Ray wallsmm Hffman Estates, 2,276,557 5/1942 Woodhead 339/103 0 x 2,455,102 ll/l948 Temple 338/240 x 2,594,921 4/1952 Hansard 338/24l x [73] Asslgnee' a 5 2 g lmanufactunng 3,213,263 10/1965 Steenbergen.... 219/523 x g 1 3,310,657 3/1967 Samoro, Jr. 219/523 [22] Filed; My 1973 3,324,448 6/1967 Von HOIZ 339/103 0 3,354,420 11/1967 Mineck 339/103 R [21] Appl. NO; 383,453 3,50l,737 3/1970 Harris et a]. 339/103 R X 52 us. 01 219/535, 219/523, 338/241, Primary Examinervolodymyr y y 339/103 C [51] Int. Cl. H05b 3/58 1 57 ABSTRACT [58] Field of Search 219/523, 535; 338/238, A Cartridge or band heater having an internally 338/239 242; 369/10? 103 c threaded bushing secured thereof affording a secure mounting for electric wires or a conduit containing [56] References Clted UNITED STATES PATENTS 2,003,175 .5/1935 Daly ..'..'338/238X such wires.

4 Claims, 3 Drawing Figures ELECTRIC HEATER The invention relates to improvements in cartridge and band heaters and is more especially concerned with the provision on such heaters of novel means to facilitate connecting flexible armored cable or a rigid conduit thereto. More particularly, the cartridge or band heater is fitted on its connection end with a bushing that is brazed or otherwise integrally secured thereon and which is internally threaded to receive a conventional fitting of a type used to secure a cable or conduit to a mounting. Cartridge heaters are generally used where concentrated heat is desired and space is limited. Such uses include, but are not limited to, heating of dies, platens, process machinery, molds,melting pots and package machinery sealing jaws.

It is therefore an object of the invention to provide cartridge and band heaters of improved construction.

Another object is to provide a heater band or cartridge with novel means to secure an armored cable or conduit thereto.

Another object is to provide a heater band or cartridge with an integral female bushing.

Another object is to provide a cartridge or band heater of the character referred to which is not difficult or expensive to manufacture, is very easy to use and install and which is highly efficient in use.

Other objects and advantages of the invention will become apparent with reference to the following description and accompanying drawings.

In the drawings: FIG. I is a perspective view of a cartridge heater embodying the invention. I

FlG. 2 is a side elevational view of the cartridge heater showing it connected to a flexible cable and partly in section.

FIG. 3 is an elevational view of a band heater embodying the invention and showing parts in section.

Referring to the exemplary embodiments of the invention shown in the accompanying drawings, and particularly to FIGS. 1 and 2, the cartridge heater 11 includes a stainless steel shell emclosing a heater (not shown) which has lead wires 12 extending from one end for connection with a source of electric current. For a purpose to be made apparent presently, the end of the cartridge having the wires 12 extending therefrom is provided with a bushing 13, that is brazed or otherwise fixedly secured to the cartridge. This bushing projects beyond the related end of the cartridge and is internally threaded, as at 14.

In use, the wires 12 are connected, as at 15, to the ends of wires 16 contained in a sheathed cable 17 which is connected to a source of electric current. The

' insulated connections are worked back into the interior of the bushing, as shown. The sheathed cable is then secured against withdrawal, and the connections 15 are concealed, by a conventional externally threaded fitting 18 which is threadedly engaged with the internal threads 14 of bushing 13. The fitting includes the usual movable clamp strap 19, which is held firmly against the sheathed cable 17 by screws 21.

In the FIG. 3 illustration of a band heater 22, said heater is provided with a bushing 13 that is brazed or welded to the outside surface thereof and which has lead-in wires 23 extending therethrough. In this embodiment, the wires 23 are each connected within the bushing to one of a pair of wires 24 leading to a source of electric current supply. An externally threaded fitting 25 is screw-threaded into the bushing as previously described. In this embodiment, there is shown a different type of fitting which is formed with a clamp portion 26 designed to receive and clamp the end of a rigid conduit 27 or a flexible armored cable.

The lead-in wires 12 or 23 may be lengthened as desired, and preferably they may be connected remote from the heater as to keep the point of connection as cool as possible. Also, the bushing 13 may be hexagonal or of any other desired straight sided shape, instead of cylindrical as shown, where the assembly is designed to bear against an adjacent member to prevent relative turning or of a shape required for grasping by a tool.

It should be evident that either type of clamp fitting 18 or 25 may be used with either type of heater illustrated, such use being determined by the type of external wiring used. Also, it is apparent that there is provided a firm connection between the cartridge or band heater and its connecting wires.

Although I have described preferred embodiments of my invention, in considerable detail, it will be understood that the description thereof is intended to be illustrative rather than restrictive, as details of the structure may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact construction shown and described.

I claim:

1. An electric heater having flexible lead-in wires extending therefrom and an electrical heating element, a metal housing for said element, electrical insulation for said element and wires, and a metal bushing and clamp assembly, said assembly comprising an internally threaded metal bushing fixedly secured at one of its ends to one end of said metal housing and through which said lead-in wires extend, electrically insulated flexible current supply wires electrically connected to said lead-in wires, and an externally threaded rigid clamp fitting through which said supply wires extend, said clamp fitting being screw threaded into said bushing, said supply wires being secured to said clamp fitting.

2. The heater recited in claim 1, in which the heater is a cartridge.

3. The heater recited in claim 1, in which the wire connections are enclosed within the bushing and fitting.

4. The heater recited in claim 1, in which the heater is a band and the bushing is brazed to the outside surface of the band and projects radially therefrom. 

1. An electric heater having flexible lead-in wires extending therefrom and an electrical heating element, a metal housing for said element, electrical insulation for said element and wires, and a metal bushing and clamp assembly, said assembly comprising an internally threaded metal bushing fixedly secured at one of its ends to one end of said metal housing and through which said lead-in wires extend, electrically insulated flexible current supply wires electrically connected to said lead-in wires, and an externally threaded rigid clamp fitting through which said supply wires extend, said clamp fitting being screw threaded into said bushing, said supply wires being secured to said clamp fitting.
 2. The heater recited in claim 1, in which the heater is a cartridge.
 3. The heater recited in claim 1, in which the wire connections are enclosed within the bushing and fitting.
 4. The heater recited in claim 1, in which the heater is a band and the bushing is brazed to the outside surface of the band and projects radially therefrom. 